Exam 1 Review Notes: HSC4501

Review for Exam 1

What Is Epidemiology?

  • Epidemiology is defined as the study of the distribution and determinants of health-related states or events in specified populations.

  • It also involves the application of this study to control and prevent health problems.

Pioneers of Epidemiology

  • Edward Jenner: Pioneer of the smallpox vaccine.

  • Ignaz Semmelweis: Early pioneer of antiseptic (washing hands) procedures.

  • John Snow: Considered one of the fathers of modern epidemiology due to his investigations into cholera epidemics in England.

Primary, Secondary, and Tertiary Prevention

  • Primary Prevention:

    • Focuses on preventing people from getting the disease before they acquire it.

  • Secondary Prevention:

    • Objective is to reduce the progress of disease and improve survival through early detection.

  • Tertiary Prevention:

    • Aims to reduce the limitation of disability from disease and improve quality of life after a disease has occurred.

Multifactorial Etiology in Chronic Disease Epidemiology: General Models of Causation

  1. Epidemiology Triangle

  2. Rothman’s Causal Pies

  3. Web of Causation

Necessary and Sufficient Cause

  • Necessary and Sufficient Cause: If only Factor A causes disease, then Factor A is necessary and sufficient. The disease will always occur when Factor A is present, and will never occur when Factor A is absent.

  • Necessary but Not Sufficient Cause: If factors A, B, and C are all needed to cause disease, then Factor A is necessary but not sufficient. Factor A must be present, but it alone is not enough to cause the disease.

  • Sufficient but Not Necessary Cause: If Factor A or Factor B or Factor C can cause disease on their own (independently), then Factor A is sufficient but not necessary. Factor A alone can cause the disease, but the disease can also occur due to other factors.

  • Neither Sufficient nor Necessary Cause: If a combination of Factor A and Factor B is needed to cause disease, but a different combination of factors (like Factor C and D or Factor E and F) can also lead to disease, then Factor A is neither sufficient nor necessary. This means Factor A is not required for the disease to occur, nor can it cause the disease on its own.

    • Example: Human papillomavirus (HPV) infections are known to cause cervical cancer. The worldwide HPV prevalence in cervical carcinomas is 99.7\%, indicating that HPV-negative carcinoma is extremely uncommon. In this case, HPV is a necessary but not sufficient cause (as other factors are also needed, even if HPV is almost always present).

  • Visual Representation (Figure 1-4):

    • This figure depicts three sufficient causes (Cause I, Cause II, Cause III) for an adverse health outcome.

    • Each combination of factors within a